<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- This file documents the GNU Assembler "as".

Copyright (C) 1991-2016 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, with no Front-Cover Texts, and with no
Back-Cover Texts.  A copy of the license is included in the
section entitled "GNU Free Documentation License".
 -->
<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
<head>
<title>Using as: i386-Float</title>

<meta name="description" content="Using as: i386-Float">
<meta name="keywords" content="Using as: i386-Float">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="index.html#Top" rel="start" title="Top">
<link href="AS-Index.html#AS-Index" rel="index" title="AS Index">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="i386_002dDependent.html#i386_002dDependent" rel="up" title="i386-Dependent">
<link href="i386_002dSIMD.html#i386_002dSIMD" rel="next" title="i386-SIMD">
<link href="i386_002dJumps.html#i386_002dJumps" rel="prev" title="i386-Jumps">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.indentedblock {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
div.smalllisp {margin-left: 3.2em}
kbd {font-style:oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nocodebreak {white-space:nowrap}
span.nolinebreak {white-space:nowrap}
span.roman {font-family:serif; font-weight:normal}
span.sansserif {font-family:sans-serif; font-weight:normal}
ul.no-bullet {list-style: none}
-->
</style>


</head>

<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
<a name="i386_002dFloat"></a>
<div class="header">
<p>
Next: <a href="i386_002dSIMD.html#i386_002dSIMD" accesskey="n" rel="next">i386-SIMD</a>, Previous: <a href="i386_002dJumps.html#i386_002dJumps" accesskey="p" rel="prev">i386-Jumps</a>, Up: <a href="i386_002dDependent.html#i386_002dDependent" accesskey="u" rel="up">i386-Dependent</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Floating-Point-8"></a>
<h4 class="subsection">9.15.9 Floating Point</h4>

<a name="index-i386-floating-point"></a>
<a name="index-floating-point_002c-i386"></a>
<a name="index-x86_002d64-floating-point"></a>
<a name="index-floating-point_002c-x86_002d64"></a>
<p>All 80387 floating point types except packed BCD are supported.
(BCD support may be added without much difficulty).  These data
types are 16-, 32-, and 64- bit integers, and single (32-bit),
double (64-bit), and extended (80-bit) precision floating point.
Each supported type has an instruction mnemonic suffix and a constructor
associated with it.  Instruction mnemonic suffixes specify the operand&rsquo;s
data type.  Constructors build these data types into memory.
</p>
<a name="index-float-directive_002c-i386"></a>
<a name="index-single-directive_002c-i386"></a>
<a name="index-double-directive_002c-i386"></a>
<a name="index-tfloat-directive_002c-i386"></a>
<a name="index-float-directive_002c-x86_002d64"></a>
<a name="index-single-directive_002c-x86_002d64"></a>
<a name="index-double-directive_002c-x86_002d64"></a>
<a name="index-tfloat-directive_002c-x86_002d64"></a>
<ul>
<li> Floating point constructors are &lsquo;<samp>.float</samp>&rsquo; or &lsquo;<samp>.single</samp>&rsquo;,
&lsquo;<samp>.double</samp>&rsquo;, and &lsquo;<samp>.tfloat</samp>&rsquo; for 32-, 64-, and 80-bit formats.
These correspond to instruction mnemonic suffixes &lsquo;<samp>s</samp>&rsquo;, &lsquo;<samp>l</samp>&rsquo;,
and &lsquo;<samp>t</samp>&rsquo;. &lsquo;<samp>t</samp>&rsquo; stands for 80-bit (ten byte) real.  The 80387
only supports this format via the &lsquo;<samp>fldt</samp>&rsquo; (load 80-bit real to stack
top) and &lsquo;<samp>fstpt</samp>&rsquo; (store 80-bit real and pop stack) instructions.

</li><li> <a name="index-word-directive_002c-i386"></a>
<a name="index-long-directive_002c-i386"></a>
<a name="index-int-directive_002c-i386"></a>
<a name="index-quad-directive_002c-i386"></a>
<a name="index-word-directive_002c-x86_002d64"></a>
<a name="index-long-directive_002c-x86_002d64"></a>
<a name="index-int-directive_002c-x86_002d64"></a>
<a name="index-quad-directive_002c-x86_002d64"></a>
Integer constructors are &lsquo;<samp>.word</samp>&rsquo;, &lsquo;<samp>.long</samp>&rsquo; or &lsquo;<samp>.int</samp>&rsquo;, and
&lsquo;<samp>.quad</samp>&rsquo; for the 16-, 32-, and 64-bit integer formats.  The
corresponding instruction mnemonic suffixes are &lsquo;<samp>s</samp>&rsquo; (single),
&lsquo;<samp>l</samp>&rsquo; (long), and &lsquo;<samp>q</samp>&rsquo; (quad).  As with the 80-bit real format,
the 64-bit &lsquo;<samp>q</samp>&rsquo; format is only present in the &lsquo;<samp>fildq</samp>&rsquo; (load
quad integer to stack top) and &lsquo;<samp>fistpq</samp>&rsquo; (store quad integer and pop
stack) instructions.
</li></ul>

<p>Register to register operations should not use instruction mnemonic suffixes.
&lsquo;<samp>fstl %st, %st(1)</samp>&rsquo; will give a warning, and be assembled as if you
wrote &lsquo;<samp>fst %st, %st(1)</samp>&rsquo;, since all register to register operations
use 80-bit floating point operands. (Contrast this with &lsquo;<samp>fstl %st, mem</samp>&rsquo;,
which converts &lsquo;<samp>%st</samp>&rsquo; from 80-bit to 64-bit floating point format,
then stores the result in the 4 byte location &lsquo;<samp>mem</samp>&rsquo;)
</p>
<hr>
<div class="header">
<p>
Next: <a href="i386_002dSIMD.html#i386_002dSIMD" accesskey="n" rel="next">i386-SIMD</a>, Previous: <a href="i386_002dJumps.html#i386_002dJumps" accesskey="p" rel="prev">i386-Jumps</a>, Up: <a href="i386_002dDependent.html#i386_002dDependent" accesskey="u" rel="up">i386-Dependent</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
</div>



</body>
</html>
